biology quiz 2.1 sg

Characteristic of Living Things

Made of cells, use energy, respond to environment, grow and develop, reproduce.

Example of a Living Thing

A dog—made of cells, eats food for energy, barks at strangers, grows, and reproduces.

Example of a Nonliving Thing

A rock—does not grow, reproduce, or use energy.

Why Classification Can Be Unclear

Some things (like viruses) show some traits of life but not all.

Atom

The smallest unit of matter.

Element

A pure substance made of only one kind of atom.

Electrons

Negatively charged particles that orbit the nucleus of an atom.

Atomic Number

The number of protons in the nucleus of an atom.

Molecule

Two or more atoms bonded together.

Covalent Bond

A chemical bond formed when atoms share electrons.

Backbone of Life

Carbon can form 4 bonds, making chains, rings, and complex molecules.

Versatile Carbon

Can bond with many elements, form single, double, or triple bonds, and create diverse molecules.

Macromolecules of Life

Carbohydrates, lipids, proteins, nucleic acids.

Monomer

A small building block molecule.

Polymer

Many monomers joined together.

Monomer of Carbohydrates

Monosaccharides (simple sugars like glucose).

Monomer of Proteins

Amino acids.

Monomer of Nucleic Acids

Nucleotides.

Do Lipids Have a Monomer?

No, but they are made of glycerol + fatty acids.

Examples of Lipids

Fats, oils, waxes, steroids.

Function of Carbohydrates

Provide energy and structure.

Function of Lipids

Store energy, insulate, and form cell membranes.

Function of Proteins

Build body structures, speed up reactions (enzymes), transport molecules.

Function of Nucleic Acids

Store and transmit genetic information (DNA, RNA).

Carbon Backbone of Carbohydrates

Usually a carbon ring.

Carbon Backbone of Lipids

Long carbon chains.

Carbon Backbone of Proteins

A chain of amino acids with carbon, hydrogen, oxygen, nitrogen, sometimes sulfur.

Carbon Backbone of Nucleic Acids

A sugar (carbon ring) with a phosphate group and nitrogen base attached.